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blkcg: don't hold blkcg lock when deactivating policy

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As described in the comment of blkcg_activate_policy(),
*Update of each blkg is protected by both queue and blkcg locks so
that holding either lock and testing blkcg_policy_enabled() is
always enough for dereferencing policy data.*
with queue lock held, there is no need to hold blkcg lock in
blkcg_deactivate_policy(). Similar case is in
blkcg_activate_policy(), which has removed holding of blkcg lock in
commit 4c55f4f9ad.

Signed-off-by: Jiang Biao <[email protected]>
Signed-off-by: Wen Yang <[email protected]>
CC: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Jiang Biao 2018-04-18 08:37:18 -06:00 • committed by Jens Axboe
commit 946b81da11
1 changed files with 0 additions and 5 deletions
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5
block/blk-cgroup.c
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@ -1410,9 +1410,6 @@ void blkcg_deactivate_policy(struct request_queue *q,
__clear_bit(pol->plid, q->blkcg_pols);
list_for_each_entry(blkg, &q->blkg_list, q_node) {
/* grab blkcg lock too while removing @pd from @blkg */
spin_lock(&blkg->blkcg->lock);
if (blkg->pd[pol->plid]) {
if (!blkg->pd[pol->plid]->offline &&
pol->pd_offline_fn) {
@ -1422,8 +1419,6 @@ void blkcg_deactivate_policy(struct request_queue *q,
pol->pd_free_fn(blkg->pd[pol->plid]);
blkg->pd[pol->plid] = NULL;
}
spin_unlock(&blkg->blkcg->lock);
}
spin_unlock_irq(q->queue_lock);